Low cost and high efficiency utilization of hemihydrate phosphogypsum: Used as binder to prepare filling material

With the gradual application of hemihydrate-wet process, the comprehensive utilization of hemihydrate phosphogypsum (HPG) needs to be concerned by phosphorus chemical industry. In order to utilize HPG and control goafs in mine, HPG was used to prepare low-cost filling binder (HCM) in the work. The flexural and compressive strength for 2 h of HPG neutralized by 1.5% quicklime was 1.6 MPa, 3.2 MPa, respectively, which can meet the strength requirements of filling binder. Quicklime can shorten the setting time of HCM and improve its early strength. The HCM neutralized by 1.0-1.5% quicklime had the best strength and its dry compressive strength for 3 days reached 16.0 MPa. The compressive strength of filling body mixed by HCM and the addition of 0-160% tailings (HFM) can meet various mining methods. Moreover, the tailings improved the mine filling adaptability of HFM, and the strength loss coefficient of HFM soaked for 240 days was only 0.25. In humid environment, although the compressive strength of HFM decreased as the curing time extended, it will gradually stabilize.